This application claims the priority of German application 196 52 507.1 filed in Germany on Dec. 17, 1996, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a step bearing for a shaft of a spinning rotor which shaft is loaded by an axial force, said step bearing comprising a freely rotatable supporting ball which is disposed against a thrust bearing, against which supporting ball the shaft is supported by a front-ended supporting surface, the supporting ball being housed in a housing for lubricating grease which is supplied to the supporting surface.
A step bearing of the above type is known from U.S. Pat. No. 4,618,273. In this case, the housing for the lubricating grease is a part of a larger housing, which comprises a collecting container for used lubricating grease. When the supply of lubricating grease is used up, a fresh supply of lubricating grease can be supplied to the housing by means of a correspondingly formed lubricating grease press. The housing is not disassembled for this purpose. In a variation of the known step bearing, the collecting container can be disassembled for cleaning.
Further lubrication of the known step bearing is complicated and requires special implements.
It is an object of the present invention to construct a step bearing of the above mentioned type which can be easily relubricated.
This object has been achieved in accordance with the present invention in that the housing is arranged in a cartridge, which can be disassembled together with the supporting ball.
It is thus possible to change a used cartridge for a cartridge with a fresh supply of lubricating grease. The work involved for re-lubricating the step bearing is reduced and therefore also the cost. The cartridge is not taken apart when disassembled, but rather the supporting ball disposed therein is disassembled with the cartridge.
In place of the disassembled cartridge, a cartridge with the required supply of lubricating grease and a supporting ball is installed. The cartridge to be installed can be a used cartridge which has been accordingly prepared, that is, cleaned and provided with a new supply of lubricating grease. The used cartridge can be taken apart during preparation. The supporting ball present in the used cartridge can, as a rule, be used again.
In an advantageous embodiment of the present invention, the cartridge with the supporting ball is constructed as a disposable part. It is often not worth preparing a used cartridge, particularly when it is made of plastic, for example, as it can be manufactured cost-effectively. The supporting ball thrown away with the cartridge can also be manufactured or procured cost-effectively.
In an advantageous embodiment of the present invention, the cartridge is releasably secured to a stationary holding device. It is practical to use fixing structure which is easily released, for example clip connections, plug connections or the like.
In a further embodiment of the present invention, the cartridge can be disassembled in the opposite direction to the axial force. The work involved for relubricating is hereby further reduced.
The thrust bearing can be arranged in the housing in such a way that it is securely connected to the cartridge, for example, the thrust bearing can be attached to the bottom of the cartridge. In this case, it is purposeful for the present invention when the cartridge is arranged in an axially adjustable manner. By adjusting the axial position of the cartridge, the thrust bearing connected thereto is also axially adjusted.
In another advantageous embodiment of the present invention, the thrust bearing is arranged on a supporting part which projects into the cartridge. It is in this case purposeful for the present invention when the thrust bearing is axially adjustable by means of an adjusting part, which is connected with the supporting part for the thrust bearing.
It can be provided that the supporting part and the adjusting part are components of the cartridge and are disassembled together with same. The cartridge can in such a case be directly releasably fixed to a stationary holding device in a constant position.
In a further advantageous embodiment, the supporting part for the thrust bearing is connected with the holding device, and the cartridge is releasable from the supporting part. The cartridge is released from the supporting part for disassembling, whereby the supporting part itself remains connected with the holding device and is not disassembled. Thus only the cartridge with the supporting ball is exchanged and replaced by a cartridge with a supporting ball. The cartridge serves thus only as a housing for the supporting ball to be taken up and for the lubricating grease to be replaced. The thrust bearing remains in its position during the exchange of the cartridge with the supporting ball and does not need to be re-adjusted. It is therefore possible to construct the cartridge with a large amount of tolerance. When the cartridge is being assembled, it need not be exactly positioned. By means of this embodiment it is thus possible to renew the supply of lubricating grease in a particularly simple and cost-effective way.
In the case of the above mentioned embodiment, it is possible to fix the cartridge to the holding device by using suitable fixing structure. It is, however, also possible to fix the cartridge to the supporting part for the thrust bearing and thus to fix the cartridge only indirectly to the holding device. It is hereby possible to use additional fixing structure connected to the holding device, or to use only the supporting part for the thrust bearing for fixing the cartridge.
In an advantageous embodiment of the present invention, the supporting ball is surrounded in circumferential direction of the shaft by webs arranged at short distances to the supporting ball, which webs project inwards from the peripheral wall of the cartridge. These webs serve as supporting surfaces for the supporting ball when the shaft is removed from the step bearing. The position of the supporting ball on the webs is such that the webs are pressed into their operational position by the shaft when it is re-inserted.
In an advantageous embodiment the housing is divided by the webs into sectioned parts for the lubricating grease to be housed therein, which sectioned parts are open in the direction towards the supporting ball. The supply of lubricating grease present in the housing can for the greater part be housed in the sectioned parts.
In an advantageous embodiment of the present invention, the cartridge comprises a collecting chamber for the lubricating grease exiting out of the housing, which collecting chamber adjoins the housing and through which collecting chamber the shaft projects into the housing.